package com.jy.appmarket.newnetwork;

import java.lang.ref.SoftReference;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.TimeZone;

public final class DateUtils {

	public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";
	public static final String PATTERN_RFC1036 = "EEEE, dd-MMM-yy HH:mm:ss zzz";
	public static final String PATTERN_ASCTIME = "EEE MMM d HH:mm:ss yyyy";

	private static final String[] DEFAULT_PATTERNS = new String[] { PATTERN_RFC1036, PATTERN_RFC1123, PATTERN_ASCTIME };

	private static final Date DEFAULT_TWO_DIGIT_YEAR_START;

	public static final TimeZone GMT = TimeZone.getTimeZone("GMT");

	static {
		Calendar calendar = Calendar.getInstance();
		calendar.setTimeZone(GMT);
		calendar.set(2000, Calendar.JANUARY, 1, 0, 0, 0);
		calendar.set(Calendar.MILLISECOND, 0);
		DEFAULT_TWO_DIGIT_YEAR_START = calendar.getTime();
	}

	/**
	 * Parses a date value. The formats used for parsing the date value are
	 * retrieved from the default http params.
	 *
	 * @param dateValue
	 *            the date value to parse
	 * 
	 * @return the parsed date
	 *
	 * @throws DateParseException
	 *             if the value could not be parsed using any of the supported
	 *             date formats
	 */
	public static Date parseDate(String dateValue) throws ParseException {
		return parseDate(dateValue, null, null);
	}

	/**
	 * Parses the date value using the given date formats.
	 * 
	 * @param dateValue
	 *            the date value to parse
	 * @param dateFormats
	 *            the date formats to use
	 * 
	 * @return the parsed date
	 * 
	 * @throws DateParseException
	 *             if none of the dataFormats could parse the dateValue
	 */
	public static Date parseDate(final String dateValue, String[] dateFormats) throws ParseException {
		return parseDate(dateValue, dateFormats, null);
	}

	/**
	 * Parses the date value using the given date formats.
	 * 
	 * @param dateValue
	 *            the date value to parse
	 * @param dateFormats
	 *            the date formats to use
	 * @param startDate
	 *            During parsing, two digit years will be placed in the range
	 *            <code>startDate</code> to <code>startDate + 100 years</code>.
	 *            This value may be <code>null</code>. When <code>null</code> is
	 *            given as a parameter, year <code>2000</code> will be used.
	 * 
	 * @return the parsed date
	 * 
	 * @throws DateParseException
	 *             if none of the dataFormats could parse the dateValue
	 */
	public static Date parseDate(String dateValue, String[] dateFormats, Date startDate) throws ParseException {

		if (dateValue == null) {
			throw new IllegalArgumentException("dateValue is null");
		}
		if (dateFormats == null) {
			dateFormats = DEFAULT_PATTERNS;
		}
		if (startDate == null) {
			startDate = DEFAULT_TWO_DIGIT_YEAR_START;
		}
		// trim single quotes around date if present
		// see issue #5279
		if (dateValue.length() > 1 && dateValue.startsWith("'") && dateValue.endsWith("'")) {
			dateValue = dateValue.substring(1, dateValue.length() - 1);
		}

		for (String dateFormat : dateFormats) {
			SimpleDateFormat dateParser = DateFormatHolder.formatFor(dateFormat);
			dateParser.set2DigitYearStart(startDate);

			try {
				return dateParser.parse(dateValue);
			} catch (ParseException pe) {
				// ignore this exception, we will try the next format
			}
		}

		// we were unable to parse the date
		throw new ParseException("Unable to parse the date " + dateValue, 0);
	}

	/**
	 * Formats the given date according to the RFC 1123 pattern.
	 * 
	 * @param date
	 *            The date to format.
	 * @return An RFC 1123 formatted date string.
	 * 
	 * @see #PATTERN_RFC1123
	 */
	public static String formatDate(Date date) {
		return formatDate(date, PATTERN_RFC1123);
	}

	/**
	 * Formats the given date according to the specified pattern. The pattern
	 * must conform to that used by the {@link SimpleDateFormat simple date
	 * format} class.
	 * 
	 * @param date
	 *            The date to format.
	 * @param pattern
	 *            The pattern to use for formatting the date.
	 * @return A formatted date string.
	 * 
	 * @throws IllegalArgumentException
	 *             If the given date pattern is invalid.
	 * 
	 * @see SimpleDateFormat
	 */
	public static String formatDate(Date date, String pattern) {
		if (date == null)
			throw new IllegalArgumentException("date is null");
		if (pattern == null)
			throw new IllegalArgumentException("pattern is null");

		SimpleDateFormat formatter = DateFormatHolder.formatFor(pattern);
		return formatter.format(date);
	}

	/** This class should not be instantiated. */
	private DateUtils() {
	}

	/**
	 * A factory for {@link SimpleDateFormat}s. The instances are stored in a
	 * threadlocal way because SimpleDateFormat is not threadsafe as noted in
	 * {@link SimpleDateFormat its javadoc}.
	 * 
	 * @author Daniel Mueller
	 */
	final static class DateFormatHolder {

		private static final ThreadLocal<SoftReference<Map<String, SimpleDateFormat>>> THREADLOCAL_FORMATS = new ThreadLocal<SoftReference<Map<String, SimpleDateFormat>>>() {

			@Override
			protected SoftReference<Map<String, SimpleDateFormat>> initialValue() {
				return new SoftReference<Map<String, SimpleDateFormat>>(new HashMap<String, SimpleDateFormat>());
			}

		};

		/**
		 * creates a {@link SimpleDateFormat} for the requested format string.
		 * 
		 * @param pattern
		 *            a non-<code>null</code> format String according to
		 *            {@link SimpleDateFormat}. The format is not checked
		 *            against <code>null</code> since all paths go through
		 *            {@link DateUtils}.
		 * @return the requested format. This simple dateformat should not be
		 *         used to {@link SimpleDateFormat#applyPattern(String) apply}
		 *         to a different pattern.
		 */
		public static SimpleDateFormat formatFor(String pattern) {
			SoftReference<Map<String, SimpleDateFormat>> ref = THREADLOCAL_FORMATS.get();
			Map<String, SimpleDateFormat> formats = ref.get();
			if (formats == null) {
				formats = new HashMap<String, SimpleDateFormat>();
				THREADLOCAL_FORMATS.set(new SoftReference<Map<String, SimpleDateFormat>>(formats));
			}

			SimpleDateFormat format = formats.get(pattern);
			if (format == null) {
				format = new SimpleDateFormat(pattern, Locale.US);
				format.setTimeZone(TimeZone.getTimeZone("GMT"));
				formats.put(pattern, format);
			}

			return format;
		}

	}

}
